Many cell membrane receptors exist on the cell surface of multicellular organisms, and they receive information given from the outside of the cell and play a role of converting same to information into the cell. Physiological extracellular (intercellular) signal transduction substances (i.e., ligand) targeting cell membrane receptors can be classified into a neurotransmitter, an endocrine substance (hormone), a low molecular substance, a cell proliferation/differentiation factor (cytokine and the like), and a cell adhesion factor, and they respectively have specific affinity for targeting receptors in different secretory formats.
Various studies have conventionally been conducted utilizing the reactivity between cell membrane receptors and ligands. For example, in the treatment of malignant lymphoma and the like, there is a method which includes collecting, from the blood, CD34 positive cells, which are undifferentiated hematopoietic stem cells present in a large amount in the bone marrow and slightly present in blood, and transplanting same. It has been reported that proliferation and differentiation of CD34 positive cells, increase in the engraftment to bone marrow, and recovery of hematopoietic ability can be promoted by using a ligand (antibody) that activates the thrombopoietin (TPO) receptor present on the membrane surface of CD34 positive cells (patent document 1).
However, when a ligand that activates a TPO receptor is taken into the body and the blood concentration of the ligand changes, a different disease may be caused.
On the other hand, a method of immobilizing a ligand (notch ligand delta 1) on a resin has been reported to achieve ex vivo growth of CD34 positive cell while maintaining the undifferentiated state thereof (patent document 2).
However, in the aforementioned method, immobilization of a ligand on general organic resins (polymethyl methacrylate and the like) requires a pre-treatment of the resin, which in turn problematically increases time and labor of operation.
On the other hand, patent document 3 reports a biological function fiber provided with a biomolecule bonded to a polymer.